1. Field of the Invention
The present invention generally relates to a wireless communication system and, more particularly, to a physical channel transmission/reception method between a base station and a terminal using inter-eNB carrier aggregation in a wireless communication system.
2. Description of the Related Art
Wireless communication systems have evolved into high-speed, high-quality wireless packet data communication systems to provide data and multimedia services beyond the early voice-oriented services. Recently, various mobile communication standards, such as High Speed Downlink Packet Access (HSDPA), High Speed Uplink Packet Access (HSUPA), Long Term Evolution (LTE), and LTE-Advanced (LTE-A) defined in 3rd Generation Partnership Project (3GPP), High Rate Packet Data (HRPD) defined in 3rd Generation Partnership Project-2 (3GPP2), and 802.16 defined in IEEE, have been developed to support high-speed, high-quality wireless packet data communication services.
As a representative broadband wireless communication standard, LTE adopts Orthogonal Frequency Division Multiple Access (OFDMA) in the downlink and Single Carrier Frequency Division Multiple Access (SC-FDMA) in the uplink. In such multiple access schemes, the user-specific data and/or control information are mapped to time-frequency resources without overlapping each other, i.e. maintaining orthogonality, to identify the user-specific data and/or control information.
The LTE system adopts Hybrid Automatic Repeat reQuest (HARQ) for retransmitting the data that has failed in decoding in the physical layer. HARQ is a technique for ensuring reliability of data transmission in such a way that a receiver transmits a Negative Acknowledgement (NACK) to a transmitter to request for retransmission of the data that has failed in decoding in the physical layer. The receiver combines the retransmitted data with the previously transmitted data to increase data reception performance. If the data are decoded successfully, the receiver transmits an ACK to the transmitter, such that the transmitter transmits next data.
In a broadband wireless communication system, one of the significant factors to provide high-speed wireless data service is bandwidth scalability for dynamic resource allocation. For example, the Long Term Evolution (LTE) system can support the bandwidths of 20/15/10/5/3/1.4 MHz. The carriers can provide services with at least one of the bandwidths, and the user equipment can have different capabilities such that some support only 1.4 MHz bandwidth and others up to 20 MHz bandwidth.
The LTE-Advanced (LTE-A) system, aiming at achieving the requirements of the IMT-Advanced service, can provide broadband service by aggregating carriers up to 100 MHz. The LTE-A system needs the bandwidth to be wider than that of LTE system for high-speed data transmission. Simultaneously, the LTE-A system needs to be backward compatible with the LTE system such that LTE User Equipments (UEs) can access the services of the LTE-Advanced system.
For this purpose, the entire system bandwidth of the LTE-A system is divided into sub-bands or component carriers that have a bandwidth supporting transmission or reception of the LTE UE and can be aggregated for supporting the high speed data transmission of the LTE-A system in the transmission/reception process of the legacy LTE system per component carrier.
FIG. 1 illustrates the configuration of a radio access network of a conventional LTE-A system capable of carrier aggregation.
FIG. 1 shows an evolved Node B (eNB) supporting aggregation of two component carriers (CC#1 and CC#2) having the center frequencies of f1 and f2 respectively. CC#1 and CC#2 belong to the same eNB 102. The eNB 102 has coverage areas 104 and 106 corresponding to the respective component carriers. In the LTE-A system capable of carrier aggregation, the data and control information for data communication are transmitted on the respective component carriers. The network configuration of FIG. 1 can be applicable for uplink component carrier aggregation as well as downlink component carrier aggregation.
However, the conventional LTE-A system is restricted to intra-eNB carrier aggregation. The present invention provides an inter-eNB carrier aggregation method, as discussed below.